Adsorptive retention of copper from acidic mine water at the disused sulphide mine at Løkken, central Norway––initial experiments using olivine

This paper investigates the chemical potential of using forsterite olivine to remove copper from acidic mine water through the actions of neutralisation and adsorption. The study was initiated by The Norwegian Directorate of Mining in order to asses the potential for employing such a concept as a remediation measure at the disused sulphide mine at Lّkken in central Norway. A number of batch experiments have been conducted in order to study a suspension system containing olivine flour and an acidic synthetic mine water solution. The synthetic solution had an initial pH close to 3 and contained 15 mg/l copper, 50 mg/l zinc and various amounts of iron. With iron present in the system, both the neutralisation isotherm and the retention isotherm exhibited an initial rapid increase before separate pH and retention maxima were reached. After this stage, a gentle decrease was observed for both parameters as a function of reaction time. This can be explained by the oxidation and precipitation of iron. With 250 mg/l of iron in solution and a solid/solution ratio of 10 g/l, approximately 79% retention was obtained after 10 min of reaction time. During the following desorption phase retention was significantly reduced. Further investigations are required in order to assess the practical feasibility of the concept.